Image-Potential States and Charge Carrier Dynamics in Carbon Nanotubes

Mikhail Zamkov, Nathan Woody, Shan Bing, Himadri Chakraborty, Arifa Habib, Zenghu Chang, Thumm Uwe, Patrick Richard
(James R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506-2604)

We have performed a theoretical study indicating the existence of low angular momentum image-potential states near surfaces of carbon nanotubes, and aimed our current efforts at their experimental investigation by means of time- and angle-resolved photoemission. Image-potential states are confined between the self-induced image potential on the vacuum side and the surface barrier, created by the central ascent in the transverse nanotube potential. Experimentally, a UV laser pump pulse is used to promote the electrons from the valence band to both the image-potential states and unoccupied levels in the conduction band. A IR laser probe pulse, delayed with respect to the first one, photoionizes the electron and the resulting kinetic energy is measured with a time-of-flight spectrometer. The measurements of charge carrier dynamics and image-potential states obtained for multi walled carbon nanotubes will be presented.

This work was supported by the Chemical Sciences, Geosciences and Biosciences Division,
Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

Submitted to DAMOP, May 2004 in Tucson, AZ.

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